Daikin ZQG71~140L7V1B Service Manual page 213

ESIE12-06
CHECK 8
Check for Excessive Refrigerant Charging
As criteria for judging whether refrigerant is excessively charged or not, refer to the following operating
conditions.
<Diagnosis of excessive refrigerant charging>
In cooling operation
(1) Because high pressure rises due to excessive charging, overload control is carried out and capacity tends
to run short.
(2) Considering pressure load, compressor discharge pipe temperature is low.
(3) Subcooled degree of condensate liquid becomes large. Therefore, temperature of blown air passing
through subcooled part decreases in heating operation.
Cooling
High pressure
(∗1)
Low pressure
(∗2)
Compressor
frequency
Electronic
expansion valve
Suction
superheat degree
Discharge
superheat degree
Adequate level
Heating
High pressure
Low pressure
Compressor
frequency
Electronic
expansion valve
Suction
superheat degree
Discharge
superheat degree
Adequate level
Cooling
1
High Pressure
2
Low Pressure
3 This measured temperature is used to calculate the equivalent saturation pressure of the
Service Diagnosis
As compressor frequency
decreases, low pressure rises.
Maximum frequency
Compressor frequency
increases in order to
maintain low pressure.
Suction superheat degree is approx. 0 deg.
(Degree of excessive refrigerant charging)
(∗1)
(∗2)
As compressor frequency
decreases, low pressure rises.
Compressor frequency
decreases in order to
maintain high pressure.
Suction superheat degree is approx. 0 deg.
(Degree of excessive refrigerant charging)
Intermediate heat
exchanger
thermistor (3)
Pressure sensor
refrigerant.
(Refer to P.210.)
Troubleshooting by Remote Controller
Compressor frequency
decreases due to high
pressure protection control
Minimum frequency
Electronic expansion valve
opening degree decreases
due to wet protection control
Minimum opening degree
Excessive charge
Minimum frequency
Electronic expansion valve
opening degree decreases
due to wet protection control
Minimum opening degree
Excessive charge
Heating
1
Pressure sensor
High Pressure
2
Intermediate heat
Low Pressure exchanger
thermistor (3)
201